Laser beam machining device and laser beam machining method

ABSTRACT

A laser beam machining device, which can automatically machine a plurality of workpieces in sequence, is disclosed. A plurality of pallets supporting workpieces are stored in a pallet storing station in a shelved manner by means of a pallet transport device. A pallet drawn out from the pallet storing station by means of a pallet transport device is transported into the laser beam machine. After laser beam machining is done, the pallet supporting the machined workpiece is stored in a predetermined location in the pallet storing station by means of the pallet transport device.

TECHNICAL FIELD

The present invention relates to a laser beam machining device, whichirradiates a laser beam to a work piece to perform a cutting operationand a laser beam machining method.

BACKGROUND ART

Japanese Examined Utility Model Publication 62-8957 and JapaneseUnexamined Patent Publication 60-30596 disclose a laser beam machiningdevice of this type, which transports a workpiece to a working positionwhere laser beam machining is carried out.

The workpiece transport device disclosed in Japanese Examined UtilityModel Publication No. 62-8957 includes an intermediate conveyer, inwhich an upper transport passage and a lower transport passage areopposed to a laser beam machine. A transport-in conveyer is located at afirst side of the intermediate conveyer. The transport-in conveyervertically moves between positions corresponding to the upper transportpassage and the lower transport passage. A transport-out conveyer islocated at a second side of the intermediate conveyer. The transport-outconveyer vertically moves between positions corresponding to the uppertransport passage and the lower transport passage.

When the transport-in and the transport-out conveyers are placed at aposition corresponding to the upper transport passage, and when a palletcarrying a workpiece is placed on the transport-in conveyer, the palletis transported into the upper passage of the intermediate conveyer fromthe transport-in conveyer. The workpiece is machined by means of thelaser beam machine, and simultaneously, the pallet carrying the machinedworkpiece is transported onto the transport-out conveyer from the uppertransport passage of the intermediate conveyer. Further, after themachined workpiece is removed from the pallet, the transport-in andtransport-out conveyers are lowered to the position corresponding to thelower transport passage. With both conveyers in this position, the emptypallet is transported back to the transport-in conveyer from thetransport-out conveyer via the lower transport passage of theintermediate conveyer.

A workpiece transport device disclosed in Japanese Unexamined PatentPublication No. 60-30596 includes a work station for the laser beammachine. A first setting station for attaching a workpiece on a palletis provided at a first side thereof. A second setting station forremoving the workpiece from the pallet is provided at a second sidethereof. A conveyer for returning the pallet is provided between thefirst and second stations, detouring around the work station.

After a workpiece is mounted on the pallet at the first station, thepallet is transported to the work station from the first station. Theworkpiece is cut by the machine and, simultaneously, the pallet carryingthe machined workpiece is transported to the second station from thework station. Further, at the second station, after the machinedworkpiece is removed from the pallet, the empty pallet is transportedback to the first station from the second station by means of theconveyer that makes a detour around the work station.

These conventional devices have their first and second stations spacedat opposite sides of the work station. This arrangement precludes thepossibility of attaching and removing a workpiece at a single station.Therefore, it is difficult to automate the workpiece attaching andremoving operations in order to achieve unmanned operation.

Furthermore, in other conventional devices, each workpiece should bechucked before the workpiece is transported into the work station. Inthis situation, each workpiece is stamped by the laser beam at themachining position. A micro-joint method is used to prevent the stampedportions from falling. Therefore, the connecting portion of theworkpiece treated by the micro-joint method should be broken off with ahammer. The broken-off portion of the workpiece must be ground forfinishing. Thus, the process is extremely troublesome.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a laserbeam machining device and a laser beam machining method that permitsmounting and removal of a workpiece at a single place.

Another object of the present invention is to provide a laser beammachining device and a laser beam machining method, which can store aplurality of pallets carrying workpieces into a stocker having multiplestages. By automating the pallet transporting operation, the workpieceswithin the stocker can be machined in an unmanned operation. Therefore,continuous machining is achieved.

A further object of the present invention is to provide a laser beammachining device and a laser beam machining method that do not requireany additional or special treatment to the machined workpiece.

The present invention achieves the foregoing objectives by providing alaser beam machining device having a stocker for storing a plurality ofpallets in a shelved manner. Each of the pallets securely carries asingle workpiece. The pallets are transferred to and machined by a laserprocessing machine, one by one. The laser beam machining apparatusincludes a pallet handling device for selectively drawing a pallet outof the stocker and replacing a pallet into the stocker. Also included isan intermediate transport station located between the stocker and thelaser processing machine. The intermediate transport station selectivelyreceives pallets drawn out of the stocker and supplies the pallets tothe laser processing machine. Also included is a transfer device forautomatically transferring pallets from predetermined positions in thestocker to the laser machine via the intermediate transfer stationbefore the workpiece is machined and from the laser machine to theintermediate transfer station after the workpiece is machined. Theworkpiece is kept free from direct contact with the transfer device.

Also, the invention .includes a method of laser beam machiningworkpieces with a laser processing machine. The workpieces are carriedon pallets which are held by shelves in a stocker. The method includessteps of: drawing one of the pallets out of the stocker with a workpiecehandling device to an intermediate station; transferring the withdrawnpallet from the intermediate station to a laser processing station witha transferring device; machining the workpiece carried on the palletwith the laser machining machine at the laser processing station;transferring the pallet from the laser processing station back to theintermediate station with the transferring device; and replacing thepallet in a predetermined position in the stocker. Each step isperformed while maintaining the workpiece free from direct contact withthe transferring device and the handling device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a laser beam machining device accordingto a first embodiment of the present invention;

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a partial front view of FIGS. 1 and 2;

FIG. 4 is an enlarged cross sectional view showing a stocker of thelaser beam machining device of FIG. 2;

FIG. 5 is a partial enlarged cross sectional view taken along line A--Aof FIG. 4;

FIG. 6 is a partial enlarged cross sectional view taken along line B--Bof FIG. 4;

FIG. 7 is a partial enlarged cross sectional view taken along line C--Cof FIG. 4;

FIG. 8 is an enlarged plan view showing an intermediate transportstation and secondary transport device in the laser beam machiningdevice of FIG. 2;

FIG. 9 is an enlarged side cross sectional view showing the intermediatetransport station;

FIG. 10 is an enlarged side cross sectional view showing a secondarytransport device;

FIG. 11 is an enlarged front view showing a pallet thrust mechanism ofthe secondary transport device;

FIG. 12 is an enlarged front view showing a pallet drawing mechanism ofthe secondary transport device;

FIG. 13 is an enlarged plan view showing the work station of the laserbeam machining device shown in FIG. 2;

FIG. 14 is an enlarged cross sectional view substantially taken alongline D--D of FIG. 13;

FIG. 15 is an enlarged cross sectional view taken along line G--G ofFIG. 13;

FIG. 16 is an enlarged plan view showing the setting station in thelaser beam machining device shown in FIG. 2;

FIG. 17 is an enlarged front view of the setting station;

FIG. 18 is an enlarged side cross sectional view showing the settingstation;

FIG. 19 is an explanatory diagram showing the transporting sequence ofthe pallets under unmanned operation;

FIG. 20 is an explanatory diagram showing the transporting sequence ofthe pallets under manned operation;

FIG. 21 is an explanatory diagram showing transporting sequence of thepallets under manned operation;

FIG. 22 is a perspective view showing the pallet;

FIG. 23 is a cross sectional view showing a work clamp mechanism locatedat the pallet;

FIG. 24 is a block diagram showing the electrical configurationaccording to this embodiment;

FIG. 25 is a flowchart showing the operation of a controller underunmanned operation;

FIG. 26 is a flowchart showing the operation of the controller undermanned operation;

FIG. 27 is a flowchart showing an interruption program indicated in FIG.26;

FIG. 28 is a perspective view showing a laser beam machining deviceaccording to a second embodiment of the present invention;

FIGS. 29(a) through 29(c) are explanatory diagrams showing theoperational sequence for a workpiece according to the second embodiment;

FIGS. 30(a) through 30(c) are explanatory diagrams showing theconsequential operations for the workpiece following FIGS. 29a-c;

FIGS. 31 and 32 show a side view and a schematic plan view showing amodified example according to the second embodiment;

FIG. 33 is a schematic plan view showing another example according tothe second embodiment; and

FIGS. 34 through 36 are schematic plan views showing the modificationwith the alternated positions of each station, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first embodiment of a laser beam machining device according to thepresent invention will now be described referring to FIGS. 1 through 29.

As shown in FIGS. 1 through 3, a stocker 1, serving as pallet storagemeans, is a generally boxed shape of which the front surface is opened.The stocker 1 has a plurality of vertically spaced shelves. The palletsP, each carrying a workpiece W, are stored in the shelves in thestocker 1. An intermediate transport station 2 is located in front ofthe stocker 1. The pallet P is transported between the stocker 1 and theintermediate station 2 by means of a pallet transport device 3 servingas pallet transport means. A work station 4 is located in the vicinityof the intermediate station 2. A secondary transport device 5 is locatedbetween the work station 4 and the intermediate station 2.

The work station 4 includes a work table 81 and a laser beam machine 6for working on a workpiece W placed on the table 81. The laser beammachine 6 includes a machine body 9, the work table 81, a laser head 7,a laser generator 10 and a chiller unit 37. When the workpiece W carriedby the pallet P is transported into the work station 4 from theintermediate station 2 via the secondary device 5, the laser beam isirradiated from the laser head 7 onto the workpiece W for executing thelaser process. The table 81 and the laser head 7 are moved according tocontrol instructions from a controller 38.

A setting station 8 is located in the vicinity of the intermediatestation 2. The pallet P is transported between the intermediate station2 and the setting station 8. At the setting station 8, the workpiece Wis mounted on or removed from the pallet P.

As shown in FIG. 22, each pallet P includes a pallet frame F and one offour supports T1-T4. The support T1-T4 is selected among the four typesaccording to the application, and attached on the frame F. The supportmay be a grid figure T1, a net figure T2, a multi spiked figure T3 or aspecially dedicated figure T4. The most suitable pallet P is selectedaccording to the type of workpiece W and the machining method.

A plurality of work clamp devices 130 are provided on the top surfacesof the pallet frame F. Each one of the clamp devices 130 clamps theworkpiece W placed on the support T1-T4 to the frame F. As shown in FIG.23, the clamp device 130 connects a clamp lever 131 to the frame F in aswingable manner about the substantially central portion. A proximal endof the clamp lever 131 is connected to a rod 133 of an air cylinder 132.The lower portion of the rod 133 of the air cylinder 132 is secured to abottom surface 134 of a cylinder chamber 137. The rod 133 is alwaysupwardly urged by the force of a spring 135 located between the chamber137 and the surface 134. Therefore, the clamp lever 131 is usually keptat the position indicated by a broken line. When the workpiece W is tobe mounted on or removed from the pallet P, air is supplied into thecylinder chamber 137 by communicating an air inlet 137a connected to thechamber 137 with an air supply E1 or E2 connected to an air supplypassage 136 and located on frames 41 and 105 of the intermediate andsetting stations 2 and 8. As the pressure of the supplied air acts onthe bottom surface 134, the bottom surface 134 is lowered by overcomingthe force of spring 135. The clamp lever 131 is swung to the releasedposition indicated by a solid line in response to the lowereddisplacement of the rod 133. After the workpiece W is mounted on orremoved from the pallet P, the clamp lever 131 is swung back to theclamping position by discharging the supplied air in the chamber 137.

The construction of the stocker 1 and the pallet transport device 3 willnow be described in detail. As shown in FIGS. 4 through 7, a pair ofattaching channels 11 are vertically arranged in parallel on the innersurface of the rear wall of the stocker 1. A plurality of laterallypaired support arms 12 are fitted to the channels 11 at predeterminedintervals to horizontally extend in the forward direction. The pallet Psupporting a workpiece W is removably placed on a pair of the supportarms 12. A number of pallets P carried by the support arms 12 are storedin the shelves of the stocker 1.

A pair of vertical rails 13 having a channel shape are secured to theright and left inner surfaces of the stocker 1. The rails 13 extendvertically in parallel. A lift 14 has a generally U-shaped cross sectionas viewed in FIG. 6. A plurality of left-right guide rollers 16 and aplurality of front-rear guide rollers 17 arranged at both sides of thelift 14 on an attaching board 15. The left-right guide rollers 16conform to grooves defined on the front and rear side surfaces of therails 13. Further, the front-rear guide rollers 17 are conform togrooves defined on the front and rear side surfaces of the verticalrails 13. Therefore, the lift 14 is movably supported along the verticalrails 13.

As shown in FIG. 5, a pair of sprockets 18 is supported by a rotaryshaft S at the upper portion of the stocker 1. Mid-portions of chains 20are mounted on the sprockets 18. A first end of each chain 20 isconnected to an attaching board 15 of the lift 14 with a fitting 21.Balance weights 22, which have a weight comparable to the lift 14, aresuspended from a second end of each chain 20. Corresponding to thesprockets 18, idling sprockets I are supported by the stocker 1, so asto guide the first ends of the chains 20 to the fittings 21. A liftmotor 23 is located on the top surface of the frame of the stocker 1. Adrive gear Ga is connected to a drive shaft of the lift motor 23 via aspeed reducer. The drive gear Ga engages with a driven gear Gb mountedon a rotary shaft S. When the lift motor 23 is driven in either theforward or backward direction, the rotation thereof is transmitted tothe sprockets 18, and then to the chains 20 via the gears Ga and Gb suchthat the lift 14 is moved up or down accordingly.

As shown in FIGS. 4, 6 and 7, a pair of horizontal rails 28 extendforwardly in parallel within side frames of the lift 14. A drawing unit29 engages and is supported by the rails 28 for frontward and rearwardmovement. A pair of protrusions 30 for receiving a pallet P from thesupport arms 12 are formed on the top surface of the unit 29. SensorsD1, D2 are provided at the front and rear ends of any one of the rails28. Detection signals from the sensors D1, D2 are transmitted to thecontroller 38. A pair of rotatable sprockets 31, 32 is located at oneside of the frame of the lift 14, each sprocket being located at aposition corresponding to the front and rear ends of the rails 28,respectively. Both end portions of a chain 33 are secured to the drawingunit 29 by fittings 34. The chain 33 runs between the pair of sprockets31 and 32.

A motor 35 for transporting a pallet is located at one exterior sidewall of the lift 14. The rear sprocket 32 is rotated, by a speed reducer36, in response to the rotational motion of the motor 35. When thesprocket 32 is rotated in the counter-clockwise direction of FIG. 7, thedrawing unit 29 is frontwardly moved out from the stocker 1 with chain33. When the rear sprocket 32 is rotated in the clockwise direction withrespect to FIG. 7, the unit 29 is moved into the stocker 1 with thechain 33.

As shown in FIG. 6, the lift 14 is vertically moved to a predeterminedposition corresponding to a pallet P stored in the stocker 1 by thedriving motion of the motor 23. After the drawing unit 29 is retractedinto the stocker 1, the lift 14 is raised by a predetermined amount suchthat the pallet P is transferred from the supporting arms 12 onto theprotrusions 30 of the unit 29. When replacing a pallet, the drawing unit29 is vertically moved, together with the lift 14, to a predeterminedposition corresponding to a pair of supporting arms 12 in the stocker 1.After the drawing unit 29 is retracted into the stocker 1, the lift 14is lowered by a predetermined amount, and the pallet P is transferredfrom the drawing unit 29 onto the supporting arms 12.

The structure of the intermediate transport station 2 will now bedescribed in detail. As shown in FIGS. 3, 8 and 9, a pair of endlessbelts Ba are located on a frame 41 and supported on a plurality of driverollers 40a, 40b, 40c, 40d so as to form belt conveyers 39. A motor 42for conveying is located on the frame 41. When the motor 42 isactivated, its rotation is transmitted to the sprocket 44b and theroller 40a by a chain 45, which is driven by a speed reducer 43 andsprocket 44a. Simultaneously the rotation is transmitted to the roller40a located at the other side, via a link shaft Cl, such that the beltconveyers 39 are integrally driven. Rollers 47 are idling rollers.

A space 46 for accommodating the lowering of the lift 14 is definedwithin the frame 41 of the intermediate station 2. The space 46corresponds to the lower portion of the lift 14. When the lift 14carrying a pallet P, which carries a workpiece W, is lowered into thespace 46 as shown in FIG. 9, the pallet P is transferred from thedrawing unit 29 to the conveyers 39. When the lift 14 is lifted upwardlyfrom the space 46 while a pallet P is placed on the belt conveyers 39,the pallet P is transferred from the belt conveyers 39 to the drawingunit 29.

The air supply E1 is located at the front portion of the intermediatetransport station 2. When the pallet P is placed at the intermediatestation 2, the air supply E1 will confront an air inlet 137a located atthe pallet P side (FIG. 23). As the air supply E1 is connected with theair inlet 137a, air is supplied into the air cylinder chamber 137.

A plurality of guide rollers 48 are provided on the frame 41 in thevicinity of the conveyers 39. The front and rear positions of the palletP are regulated in such a way that the guide rollers 48 engage with thefront and rear edges of the pallet P placed on the intermediate station2.

As shown in FIGS. 8 and 11, a pair of stopper cylinders 49 having ashock absorber function are located at both sides of the front sectionof the frame 41. Swing stoppers 50 with a roller are connected to theupper end of a piston rod. When the pallet P is to be transported fromthe work station 4 to the intermediate station 2, the stopper 50 locatedat the left side in FIG. 8 is projected upward and engages with the leftedge of the pallet P. The stopper 50 acts like a shock absorber suchthat the pallet P is stopped at a predetermined position on theintermediate transport station 2. When the pallet P is transported fromthe setting station 8 to the intermediate station 2, the stopper 50located at the right side in FIG. 8 is upwardly projected and engagesthe right edge of the pallet P such that the pallet P is stopped at apredetermined position on the intermediate station 2.

A first pallet sensor K1, formed by a proximity sensor, is located atthe front left end portion of the intermediate station 2. The firstpallet sensor K1 detects whether the pallet P is at the predeterminedposition on the intermediate station P, and transmits a detection signalto the controller 38.

As shown in FIGS. 1, 2 and 8, a memory medium 51 is provided at thefront surface of each pallet P. Each memory medium 51 stores thefollowing information in advance: type of pallet P, type of workpiece W,method for the workpiece W, and the storage position of the pallet P inthe stocker 1. According this embodiment, a bar code system is employedas the memory medium 51.

A reader 52 is located at the front portion of the intermediate station2. When a pallet P supporting a workpiece W is placed on theintermediate station 2, the memory medium 51 located on the pallet Pconfronts the reader 52. The information stored in the memory medium 51is read by the reader 52, and transmitted to the controller 38 locatedat the side of the work station 4. After that, when the pallet P istransported to the work station 4, the workpiece W is machined accordingto the information read by the reader 52. Also, the pallet P is storedin a predetermined location in the stocker 1 by means of the pallettransport device 3. However, when the controller 38 stores a sequenceprogram including pallet information in advance, that information can betransmitted when a signal indicating that the pallet has passed isconfirmed.

As shown in FIG. 2, a pallet passing sensor L, formed by a limit switch,is located at the right end portion of the intermediate station 2. Thepassing sensor L detects the movement of the pallet P from theintermediate station 2 to the work station 4, and transmits a detectionsignal to the controller 38.

The structure of the secondary transport device 5 will now be describedin detail. As shown in FIGS. 8, 10 through 12, a pair of endless beltsBb held between a plurality of rollers 56a, 56b, 56c, 56d and 56e formbelt conveyers 55 which circularly move around a frame 57. When themotor 42 is activated, its rotation is transmitted to a sprocket 58b anda roller 56a by the speed reducer 43, sprockets 58a and 58b, and a chain59. Simultaneously, the rotation is transmitted to the roller 56alocated at the other side by a link shaft C2 such that both beltconveyers 55 are integrally driven.

A pallet thrust mechanism 60 is located between the belt conveyers 55,and positively thrusts a pallet P transported from the intermediatestation 2 toward the work station 4 from the rear side of the pallet P.

More specifically, a swing lever 61 is rotatably connected to the frame57 at the central portion thereof by a support shaft (FIG. 11). Anurging roller 64 is supported at the upper end of the lever 61 by an arm63. A support lever 65 is swingably connected to the frame 57 at itslower end by a support shaft 66 such that the support lever 65 moves inparallel to the swing lever 61. The arm 63 is linked to the upper end ofthe support lever 65.

An urging cylinder 67 is swingably connected at one end to the frame 41of the intermediate station 2. A rod 68 is linked to the lower end ofthe swing lever 61. When a pallet P is transferred towards the workstation 4, the rod 68 is retracted as the rear edge of the pallet Papproaches the right end of the belt conveyers 55 (as viewed in FIG.11). Therefore, the swing lever 61 and support lever 65 are swung fromthe positions indicated by two dotted lines to the positions indicatedby solid lines in FIG. 11 such that the pallet P is urged in themachining direction by the urging roller 64.

As shown in FIGS. 8 and 12, pallet drawing mechanisms 69 are locatedabove the opposed belt conveyers 55. When the pallet P carrying themachined workpiece W is to be transported from the work station 4 to theintermediate station 2, the pallet drawing mechanisms 69 urge the palletP onto the belt conveyers 55 and draw the pallet P onto the secondarytransport device 5.

More specifically, a pair of support arms 70 are swingably connected tothe frame 57 at one end by support shafts 71. Urging rollers 72 aresupported at the opposite ends of the support arms 70 which, at times,contact the belt conveyers 55. A link shaft 73 is secured to the centralportions of the support arms 70. An urging cylinder 74 is swingablyconnected, at its lower end, with the frame 57. A pin 75 is received bythe rod of the cylinder 74. A spring 76 is located between an end of thepin 75 and the link shaft 73 such that the urging roller 72 is urgedtoward the belt conveyers 55.

The rod of the cylinder 74 is normally extended such that the urgingroller 72 is kept at a position spaced apart from the belt conveyers 55.When a pallet P is transported from the work station 4 to the transportstation 2, the rod of the cylinder 74 is retracted as the front edge ofthe pallet P (with respect to the transport direction) approaches theright end of the belt conveyer 55 (as viewed in FIG. 12). The drawing ofthe pallet P with the belt conveyers 55 is assisted by the urging roller72, which is urged against the pallet P on the belt conveyers 55 due tothe urging force of the spring 76.

The structure of the work station 4 will now be described referring toFIGS. 2 and 13 through 15. A pair of guide rails 79 are located inparallel on a frame 80. A work table 81 is movably supported on therails 79. A toothed pulley 83 is rotatably supported by the frame 80. Adrive nut 82 is fitted to the inner circumference of the pulley 83. Athreaded rod 84 is horizontally secured at the lower portion of the worktable 81 and threaded to the drive nut 82.

A motor 85 is located on the frame 80 for moving the table. A toothedbelt 87 runs between a toothed drive pulley 86 mounted on the driveshaft of the motor 85 and the toothed pulley 83. When a workpiece W isto be machined on the pallet P on the work table 81, the work table 81is moved with threaded rod 84 according to the rotation of the drive nut82 by the pulleys 86 and 83 and the toothed belt 87 as a result of therotation of the motor 85.

As shown in FIGS. 13 and 14, a plurality of transport rollers 88 arelocated on both upper front and rear edges of the work table 81. Apallet P which is to be transported from the intermediate transportstation 2 onto the work station 81 will be moved and supported by therollers 88. A plurality of guide rollers 89 are located on both upperfront and rear edges of the work table 81. Therefore, the rollers 89engage with side edges of the pallet P on the work table 81 such thatthe motion of the pallet P is regulated in the lateral direction.

A plurality of urging bodies 96 for positioning the pallet are locatedalong the rear edge of the work table 81 and are actuated with cylinders95. The pallet P is moved to a predetermined location by the bodies 96.That is, the pallet P is clamped between the urging bodies 96, which aremoved toward the pallet P by the cylinder 95, and the rollers 89. A pairof hooks 92 are swingably supported at the upper right end portion ofthe work table 81 so as to link with a rod of a cylinder 94 with levers93. When the pallet P is to be transported from the intermediatetransport station 2 to the work table 81, the hooks 92 are swung in theclockwise direction (as viewed in FIG. 14) with a cylinder 94 so as toengage with the inner right edge of the pallet P. This will draw thepallet P to a predetermined position over the work table 81. As shown inFIG. 2, a second sensor K2, formed by a proximity sensor, is located atthe right end portion of the work station 4. The sensor K2 transmits asignal to the controller 38 when the pallet P is transported to thepredetermined position on the work table 81.

As shown in FIGS. 13, a cylinder 99 is located at the right end portionof the work table 81 and extends beyond the work station 81. An urgingpiece 100 is connected to the end of the rod of the cylinder 99. Afterthe workpiece W is machined, the pallet P supporting the machinedworkpiece W is transferred from the work table 81 toward the secondarytransport device 5 by means of the urging piece 100, which is movedleftward according to the projecting motion of the piston rod of thecylinder 99. The pallet P is moved while the engagement of the urgingbodies 90 and hooks 92 are in their released positions.

The structure of the setting station 8 will now be described referringto FIGS. 1 and 16 through 18.

A pair of endless belts Bc are fitted on a plurality of rollers 104a,104b, 104c and 104d so as to form belt conveyers 103, which are locatedon a frame 105. A motor 106 for driving the belts is located at theinside of the frame 105. The rotation of the motor 106 is transmitted tosprocket 108b and the roller 104a coaxially connected with the sprocket108b via a speed reducer 107, sprockets 108aand 108b, and a transmissionchain 109. Simultaneously, the rotation is transmitted to the roller104a located at the other side, via a link shaft C3, such that both beltconveyers 103 are integrally driven. Rollers 110 are idling rollers.

A plurality of guide rollers 111 are located on the frame 105 in thevicinity of the belt conveyers 103. These rollers 111 engage with thefront and rear edges of the pallet P placed on the setting station 8such that the front and rear position of the pallet P is regulated.

As shown in FIGS. 2 and 16, elastic stoppers 112, made of rubber cushionor the like, are located at two locations on the left side frame 105.When the pallet P is transported from the intermediate transport station2 to the setting station 8, the stoppers 112 engage with the left edgeof the pallet P such that the pallet P is positioned at a predeterminedlocation on the setting station 8. A third pallet sensor K3, formed byan proximity sensor, is located at the right end portion of the settingstation 8. The pallet sensor K3 transmits a signal to the controller 38when the sensor K3 detects that the pallet P is at the predeterminedposition on the setting station 8.

As shown in FIGS. 17 and 18, a lift device 114 is located at the insideof the frame 105. When the operations of mounting a workpiece W on orremoving a workpiece W from the pallet P at the setting station 8 areconducted, the lift device 114 elevates the workpiece W from the topsurface of the pallet P.

More specifically, two sets of paired operative legs 115 and 116 arelocated at the inner bottom portion of the frame 105, on a support board117. A lift carriage 118 is supported on a top span defined betweenpaired legs 115 and 116. A pair of lift bodies 119 upwardly protrudefrom the front and rear edges of the lift carriage 118. A plurality ofballs 120 are rotatably located at the top distal portions of the liftbodies 119, which engage with the front and rear edges of the workpieceon the pallet P from the bottom side.

A pair of lift cylinders 121 are located on the support board 117.Piston rods are connected with the inner portions of the operative legs115 respectively. When the lift carriage 118 is lifted from the positionindicated by a solid line in FIG. 18, according to the actuation of thecylinder 121 as indicated by a broken line, the workpiece W is lifted bya predetermined amount from the top surface of the pallet P as the balls120 engage with bottom surface of the workpiece W. Unclamping of theworkpiece W with the pallet P is executed by supplying air to the clampdevice 130. The air supply E2 connected to the air supply passage 136 islocated at the front portion of the setting station 8. When the pallet Pis transported to the setting station 8, the air supply E2 confrontswith the air inlet 137a. The air supply E2 is similar to the air supplyE1 at the intermediate transport station 2.

The electrical configuration according to the present invention will nowbe described referring to FIG. 24. First, the electrical configurationat the input side of the controller 38 will be described. The reader 52reads the memory medium 51 placed on a pallet P (FIG. 1). The operationfor a workpiece W supported on the pallet P and the operation for themachined workpiece W will be executed according to control programsstored in the memory medium 51.

A sensor D1 (FIG. 4) transmits a detection signal to the controller 38when the sensor D1 detects the front end of the pallet P as it reachesthe fully drawn position. A sensor D2 transmits a detection signal tothe controller 38 when the sensor D2 detects the pallet P is at thefully rearward position on the support arm 12. A motor speed sensor 23adetects the number of revolutions of the lift motor 23 and transmits adetection signal according to the detected value.

The first pallet sensor K1 transmits a detection signal to thecontroller 38 when the pallet P is accurately positioned at the placewhich corresponds to the storing position for the stocker 1 on theintermediate transport station 2. The pallet passing sensor L transmitsa detection signal to the controller 38 when the pallet P is transportedfrom the intermediate station 2 to the secondary transport device 5. Asecond pallet sensor K2 transmits a detection signal to the controller38 when the pallet P is accurately positioned at the place whichcorresponds to the machining stand-by position on the work table 81 inthe work station 4. A third pallet sensor K3 transmits a detectionsignal to the controller 38 when the pallet P is accurately positionedat the predetermined position on the setting station 8.

The electrical configuration at the output side of the controller 38will be described, referring to FIG. 24, together with the flowchart inFIG. 25, which explains the operational steps.

When the pallet P is to be drawn out from the stocker 1 to theintermediate transport station 2, the controller 38 drives the motor 35such that the drawing unit 29 is drawn out of the stocker 1 (step S1).The controller 38 drives the motor 23 such that the lift 14 isvertically moved to the designated height, either upwardly ordownwardly, which corresponds to the position of the pallet P (step S2).The controller 38 drives the motor 35 such that the drawing unit 29 isinwardly moved to the position just under the selected pallet P (stepS3). When the lift 14 moves vertically, the controller 38 drives themotor 23 and calculates the position or height of the lift 14 from timeto time, according to the number of revolutions of the motor sent fromthe sensor 23a, to draw out the selected pallet P. The controller 38causes the lift 14 to ascend to the predetermined height. In the meantime, the pallet P is slightly lifted from the support arms 12 by meansof the drawing unit 29 (step S4). The controller 38 confirms the receiptof the pallet P by the drawing unit 29 according to the detection signaltransmitted from the sensor D2 (step S5). The controller 38 drives themotor 38 such that the pallet P is drawn out from the stocker 1 (stepS6). The controller 38 confirms the completion of the drawing operationaccording to the detection signal transmitted from the sensor D1 (stepS7).

The controller 38 drives the motor 23 such that the lift 14 descends tothe lowermost position in order to transfer the pallet P onto theintermediate transport station 2. In this manner, the pallet P is drawnout from the stocker 1 to the intermediate station 2 (step S8). Thecontroller 38 confirms the completion of the drawing operation accordingto the detection signal transmitted from the first sensor K1 (step S9).The controller 38 drives the motor 42 such that the belt conveyers 39are rotated to transport the pallet P to the work station 4 (step S10).

The controller 38 prepares to execute laser beam machining according tothe detection signal transmitted from the sensor L. More specifically,the controller 38 activates a first electromagnetic valve Vl so as toactivate the urging cylinder 67, and a second electromagnetic valve V2so as to activate the urging cylinder 74. By these activations, thepallet P is securely transferred from the conveyers 39 and 55 to thework table 81. The controller 38 activates a third electromagnetic valveV3 so as to drive the cylinder 95 to determine the position in the widthdirection on the work table 81. Simultaneously, the controller 38activates a fourth electromagnetic valve V4 so as to drive the cylinder94. Therefore, the pallet P is moved to the predetermined location onthe work table 81 by means of the hooks 92, and is kept at the machiningpreparation position.

The controller 38 confirms that the pallet P is at the machiningpreparation position according to the detection signal transmitted fromthe second sensor K2 (step S11). The controller 38 activates the laserbeam machine 6 to apply the laser to the workpiece W placed on thepallet P by driving the motor 85 for the X axis, and motors for the Yand Z axes (not shown) according to the pre-stored machining program(step S12). When the laser beam machining is completed (step S13), thecontroller 38 deactivates the third and fourth electromagnetic valves V3and V4 to release the pallet P.

The controller 38 drives the motor 42 in the reverse direction and,simultaneously, activates a fifth electromagnetic valve V5 such that therod of the cylinder 99 is protruded to push the pallet P toward theintermediate transport station 2. Therefore, the pallet P is transportedto the intermediate station 2 (step S14). The controller 38 confirmsthat the transport of the pallet P is completed according to thedetection signal transmitted from the first sensor K1 (step S15). Thecontroller 38 activates the motor 23 and 35 to drive the drawing unitand lift in order to restore the pallet P supporting the machinedworkpiece W to the original position in the stocker 1 (steps S16 throughS21). The controller 38 confirms that the pallet restoring operation iscompleted according to the detection signal transmitted from the sensorD2 (step S22). When a successive machining operation is required at stepS23, the controller 38 returns to step S1 to repeat the same operation.In the above-described manner, all steps can be automated.

When an operator is going to manually remove the machined workpiece W atthe setting station 8, the pallet P is transported from the work station4 to the setting station 8 via the intermediate transport station 2. Inthe flowchart shown in FIG. 26, the controller 38 executes theoperations at steps S31 through S43 similar to those of steps S1 throughS13. As the motors 42 and 106 are simultaneously activated uponcompletion of the machining operation, the pallet P is transported fromthe work station 4 to the setting station 8 via the intermediate station2 (step S44).

When the pallet P reaches the predetermined position on the settingstation 8, the third sensor K3 detects arrival of the pallet P andtransmits a detection signal to the controller 38 (step 45). After theoperator removes the machined workpiece W from the pallet P by hand orby manipulating a crane (not shown) and replaces it with a new workpieceW, the operator manipulates a switch for indicating the completion ofthe replacement operation. A signal is transmitted from the switch tothe controller 38 (step S46). The controller 38 confirms that the pallettransfer at the intermediate transfer station 2 has been completed (stepS47). The controller determines whether the pallet P should betransported to the stocker 1 or work station 4 according to the program(step S48). When the pallet P is to be stored into the stocker 1, thecontroller executes the pallet storing operation at steps S49 throughS54. On the other hand, when the pallet P is to be directly transferredfrom the setting station 8 to the work station via the intermediatestation 2, the controller 38 shifts its operation to step S40.

During the execution of the above-described steps, the controller 38 isdesigned to interrupt with another routine. More specifically, as shownin FIG. 27, in a routine to draw out the pallet P supporting theworkpiece W to be machined next from the stocker 1 to the intermediatestation 2, the controller 38 executes the operations of steps S60through S67, similar to those of steps S31 through S39. Thus, the palletP supporting the workpiece W to be machined next can be drawn out to theintermediate station 2 during laser beam machining.

The movement in the laser beam machining device under the operationalmode, which the setting station 8 also uses, will now be describedreferring to the movement of the pallet P.

As shown in FIG. 19, a plurality of the pallets supporting workpieces Ware stored beforehand in the stocker 1. More specifically, after apallet Pa supporting a first workpiece W is drawn out from a certainshelf of the stocker 1 and placed on the intermediate transport station2, the pallet Pa is transported from the intermediate station 2 to thework station 4. The first workpiece W is machined by the laser beammachine 6 at the work station 4 (progress P1). While the first workpieceW is being machined, a pallet Pb supporting a second workpiece W isdrawn out from the stocker 1 and kept at a stand-by position above theintermediate station 2. After the machining operation of the firstworkpiece W is completed, the pallet Pa supporting the machined firstworkpiece W is transported from the work station 4 to the settingstation 8, via the intermediate station 2 (P2).

The pallet Pb at the stand-by position is placed on the intermediatestation 2 by the pallet transport device 3 and is then transported fromthe intermediate station 2 to the work station 4. Simultaneously, thepallet Pa supporting the machined workpiece W is transported from thesetting station 8 to the intermediate station 2 (P3 and P4). In thiscondition, laser beam machining is done to the second workpiece Wsupported on the pallet Pb at the work station 4. Simultaneously, thepallet Pa supporting the machined workpiece W is to be stored in acertain shelf within the stocker 1 from the intermediate station 2(progresses P5 and P6).

The controller 38 returns to progress P2 and repeatedly executes theoperations of progresses P2 through P6. Therefore, pallets P supportingunmachined workpieces W stored in the stocker 1 are transported to thework station 4 one after another. Each pallet P supporting a processedworkpiece W is stored in the stocker 1 in sequence.

The transport operation of the workpiece W into/from the work station 4can be automatically executed. Therefore, the laser beam machiningdevice can be operated in an unmanned mode during the night to increaseproductivity. Even if the types of workpieces W on the pallets P storedin the stocker 1 and their machining conditions differ from one another,each workpiece W is automatically machined according to the specifiedconditions which are stored in the memory medium 51 of the respectivepallet P and are read by the reader 51 located on the intermediatestation 2. Further, since a plurality of pallets P supporting workpiecesW are stored vertically in the stocker 1. The installation space of thedevice is reduced.

As shown in progresses P7 through P9 of FIG. 19, the transport operationof the workpiece W into/from the work station 4 can be automaticallyexecuted while the operations of mounting a new workpiece W to thepallet P and removing the precessed workpiece W therefrom are executedat the setting station 8. Therefore, the machining operation of a numberof workpieces W can be continuously carried out.

In other words, when the pallet Pa supporting the first workpiece W isdrawn out from the stocker 1 onto the intermediate transport station 2by means of the pallet transport device 3, the second workpiece W can bemounted onto the pallet Pb at the station 8 (progress P7). The pallet Pasupporting the first workpiece W is transported from the intermediatestation 2 to the work station 4. Simultaneously, the pallet Pbsupporting the second workpiece W is transported from the settingstation 8 to intermediate station 2 (progress PS). Laser machining isdone to the first workpiece W on the pallet Pa. Simultaneously, thepallet Pb supporting the second workpiece W is transported and stored ina predetermined shelf in the stocker 1 by means of the pallet transportdevice 3 (progress P9).

The operations of progresses P2 through P6 are repeatedly executed. Thepallets P supporting unmachined workpieces W are continuouslytransported into the work station 4 one after another, and lasermachining is done to the transferred workpieces W in sequence.Furthermore, at progress P3, every time a pallet P supporting a machinedworkpiece W is transported into the setting station 8, the machinedworkpiece W is removed from the pallet P and an unmachined workpiece isinstalled. Therefore, according to this machining method, the operationof mounting and removing the workpiece W can be executed at a singleplace. A greater number of workpieces W than that of the storedworkpieces W in the stocker 1 can be smoothly machined in sequence. As aresult, productivity can be improved.

When laser beam machining is executed while mounting or removingworkpieces W at the setting station 8, pallets P are transported insequence as indicated in FIGS. 20 and 21.

In progresses P10 and P11 shown in FIG. 20, a pallet Pc holding anunmachined workpiece W at the setting station 8 is transported to thework station 4 via the intermediate transport station 2. After lasermachining the workpiece W on the pallet Pc, the pallet Pc supporting themachined workpiece W is transported from the work station 4 to thesetting station 8 via the intermediate station 2 or stored into thestocker 1 via the intermediate station 2. In progress P12 of FIG. 21,after a pallet Pd is drawn out from the stocker 1 and placed on theintermediate station 2 by the pallet transport device 3, the pallet Pdis transported to the setting station 8.

Therefore, by combining the operations described in FIGS. 20 and 21 withthat of FIG. 19, pallets P can be freely transported among the stocker1, work station 4 and setting station 8. Thus, laser beam machining canbe efficiently executed.

After the laser beam machining is applied, cut-off portions of theworkpiece W will remain on the pallet P. A connecting portion of theworkpiece W (a micro joint) is no longer required. Therefore, handlingof the machined workpiece W is simplified.

The second embodiment according to the present invention will now bedescribed referring to FIGS. 28 through 36.

According to this embodiment, pallet storing means is formed by atemporary stocker 209 for storing a work pallet 211 supporting aworkpiece W. The pallet 211 is transported to a work station 214, via anintermediate transport station 300. A plurality of material pallets 203,which are not directly related to the laser beam machining, areremovably supported on support arms 202 in a material stocker 201 forsupplying workpieces W. A plurality of workpieces W having a plane shapeare separated by type of material, size and thickness, etc., are placedone on top of another on each material pallet 203 according to theirtype. The pallets 203 are transported from the stocker 201 to theintermediate station 300 located at the front of the stocker 201 bymeans of a pallet transport device 204. The pallets 203 may also betransported in a reverse direction.

An setting station 205 is located at the lowest shelf within thematerial stocker 201. A selected material pallet 203 is transported tothe setting station 205 from the material stocker 201 by means of thepallet transport device 204. The setting station 205 includes a palletsupport base 206 for supporting the material pallet 203, a vacuumadhesion device 207 for adhering a sheet of workpiece W by suction tothe top of the material pallet 203, and a pair of cylinders 208 forvertically moving the vacuum adhesion device 207. A sheet workpiece W ispicked up from the top of the material pallet 203 by means of the vacuumadhesion device 207 and is fitted on the work pallet 211, which will bedescribed below.

On the other hand, the temporary stocker 209 is located in the vicinityof the material stocker 201. A plurality of work pallets 211, whichcarry either un-machined workpieces W, machined workpieces W or areempty, are stored in the vertically constructed shelves of the supportarms 202. The work pallet 211 is transported to or from the intermediatestation 300 by means of a pallet transport device 212 located at theinside of the temporary stocker 209.

The intermediate transport stations 300 and 301 are formed by a beltconveyer 213, which is located at the front of the material stocker 201and temporary stocker 209 and extends in a direction along the materialstocker 201 and temporary stocker 209. An empty work pallet 211 drawnfrom the temporary stocker 209 is transported to the front of thematerial stocker 201 and to setting station 205 by means of the pallettransport device 204. After a work pallet 211, on which the workpiece Wis mounted, is frontwardly transported by the pallet transport device204, the pallet 211 is transported to the front of the temporary stocker209 by the belt conveyer 213. The pallet 211 is then stored in thetemporary stocker 209 by the pallet transport device 212. Further, thework pallet 211 supporting a machined workpiece W is transported to theintermediate transport station 300 by the belt conveyer 213, and isstored into the temporary stocker 209 by the pallet transport device212.

Furthermore, at a setting station 222, an un-machined workpiece W can besupplied to the material pallet 204 transported from the materialstocker 201 or a machined workpiece W can be removed from a work pallet211 transported from the temporary stocker 209.

The operation of a laser beam machining system, which has theabove-described configuration, will now be described.

In this laser beam machining system, a plurality of plane shapeworkpieces W are previously separated and stored one on another in apile on the material pallets 203 by kind, size and machining method,etc., at the setting station 222. Then, the pallets 203 are stored inthe vertically constructed shelves of the material stocker 201 via beltconveyer 213 and pallet transport device 204. As shown in FIG. 29(a),when the laser machining system is in operation, the material pallet203, supporting a certain type of workpieces W, is drawn out from thematerial stocker 201 by the pallet transport device 204 and is placed onthe pallet support base 206 of the setting station 205. At this time,the vacuum adhesion device 207 is moved over the material pallet 203 bymeans of the cylinder 208.

In this condition, as shown in FIG. 29(b), the vacuum device 207 in thesetting station 205 is lowered to the workpiece W and a sheet ofworkpiece W on the material pallet 203 is adhered to the vacuum adhesiondevice 207. The vacuum adhesion device 207 with the workpiece W islifted to the original position. Then, as shown in FIG. 29(c), a certainwork pallet 211 is drawn out from the temporary stocker 209 by means ofthe pallet transport device 212 and transported to the front of thematerial stocker 201 by the belt conveyer 213. Then, it is placed in thesetting station 205, which is located underneath the vacuum adhesiondevice 207.

As shown in FIG. 30(a), the vacuum adhesion device 207 of the settingstation 205 is lowered and its suction is halted. Therefore, the sheetworkpiece W is released from the vacuum adhesion device 207 and placedon the work pallet 211. After that, the vacuum adhesion device 207 islifted to the original position. In this condition, as shown in FIG.30(b), the work pallet 211 supporting the workpiece W is moved from thesetting station 205 by means of the pallet transport device 204. Thework pallet 211 is transported to the front of the temporary stocker 209by means of the belt conveyer 213 and is then stored in a certain shelfof the temporary stocker 209 by the pallet transport device 212.

As shown in FIG. 30(c), the work pallet 211 supporting a workpiece W isdrawn out from the temporary stocker 209 by means of the pallettransport device 212 and is then transported to the work station 214along the intermediate transport station 300 to the work table. Afterthe work pallet 211 supporting the workpiece W is moved from thetemporary station 205, it can be directly transported to a work table217 of the work station 214 without storing it in the temporary stocker209. These operational steps are preferably performed according tovarious conditions regarding time and order, etc.

As shown in FIG. 30(c), at the work station 214, laser beam machining isdone to the workpiece W on the work pallet 211. After the laser beammachining is completed, the work pallet 211 supporting the machinedworkpiece W is transported to the front of the temporary stocker 209along the intermediate station 300. Then, the work pallet 211 is storedinto a certain shelf of the temporary stocker 209 by the pallettransport device 212.

When laser beam machining is to be continuous, the steps of FIGS. 29(b)and (c), and FIGS. 30(a) through (c) are repeatedly executed. When laserbeam machining is to be done to the workpiece W carried on the materialpallet 203 stored in the material stocker 201, as shown in FIG. 30(c),the pallet 203 in the setting station 205 is moved away from the settingstation 205 by means of the pallet transport device 204 and stored in acertain shelf of the material stocker 201. Then, the steps similar tothose in FIGS. 29(a) through (c) and FIGS. 30(a) through (c) areexecuted.

When the machining operation is carried out in this manner, and thenumber of the work pallets 211 supporting the machined workpieces Wexceeds a predetermined number, or a predetermined period of time sincethe machining operation was initiated has elapsed, the work pallet 211supporting the machined workpiece W is drawn out from the temporarystocker 209 by means of the pallet transport device 212. Then, the workpallet 211 is transported into the setting station 222, via intermediatetransport stations 300 and 301. Therefore, the machined workpiece W canbe removed from the work pallet 211 at the setting station 222.

As described above, those steps are set to achieve the most efficientproductivity.

Another example according to the second embodiment will now be describedreferring to FIGS. 31 through 33.

As shown in FIGS. 31 and 32, the setting station 205 is located at theother side of the intermediate transport station 300 to face theexternal front portion of the material stocker 201. The setting station205 includes a material pallet 203 for supporting a workpiece W, a beltconveyer 249 for transporting a certain work pallet 211, the vacuumadhesion device 207 for picking a sheet workpiece W from the top of thematerial pallet 203, and the cylinder 208 for vertically moving thevacuum adhesion device 207.

Therefore, according to this embodiment, the pallet 203 supporting acertain workpiece W is drawn out from the material stocker 201 by thepallet transport device 204, and placed onto the belt conveyer 249within the setting station 205. The sheet workpiece W is picked from thetop of the material pallet 203 by means of the vacuum adhesion device207. After that, while the material pallet 203 supporting the workpieceW is transported away from the setting station 205 with the conveyor249, a certain work pallet 211 is drawn out from the temporary stocker209 and transported onto the belt conveyer 249 of the setting station205 with the combined functions of the pallet transport devices 204 and212, and belt conveyer 213. Then, the sheet workpiece W is removed fromthe vacuum adhesion device 207 and placed onto the work pallet 211. Thiswork pallet 211 is transported into either the temporary stocker 209 orthe work station 214.

Therefore, according to this example, every time a sheet workpiece W ismounted on the work pallet 211, the material pallet 203 is transportedin and out. The location from which the workpiece W is to be picked upand the location of the work pallet on which the picked-up workpiece Wis to be set are designed to be different from each other and the vacuumadhesion device 207 is movably controlled between the two locations.Therefore, transporting the material pallet for every workpiece W is nolonger required.

Another example according to this embodiment will now be describedreferring to FIG. 33. According to this example, a transport passage 250is extended in one direction. A plurality of material stockers 201 and aplurality of temporary stockers 209 are located along the first side ofthe passage 250. A setting station 222 and setting station 205 arelocated along the other side portion of the passage 250. A plurality ofwork stations 214 are located along this side of the transport passage250. Each work station 214 includes a pallet transport device 251 fortransporting in/out a work pallet 211 supporting a workpiece W and alaser beam machine 215. Further, a work robot 252 is movably located onthe transport passage 250. The material pallet 203 or the work pallet211 can be transported between respective stations by means of the workrobot.

Therefore, according to this embodiment, when the workpieces W arereceived at the setting station 222 from a truck 253 by means of acrane, etc., the material pallet 203 is reciprocally transported betweenthe material stocker 201 and the setting station 205 by means of thework robot 252, and then the workpieces W are stored into the shelves ofthe material stocker 201. When laser beam machining is to be executed bythe laser beam machine 215, a sheet workpiece W is transported from thematerial pallet 203 onto the work pallet 211 by means of the work robot252 at the setting station 205. After this operation is completed, thework pallet 211 supporting the workpiece W is transported into the workstation 214. Laser beam machining is done on the workpiece W by means ofthe laser beam machine 215. Further, the work pallet 211 supporting themachined workpiece W is transported out from the work station 214 bymeans of the work robot 252 and stored in a certain temporary stocker209.

Each one of the FIGS. 34 through 36 shows other examples according tothis embodiment. In the example shown in FIG. 34, the temporary stocker209. The material stocker 201 are located in a row. The setting station205 is located at the front of the temporary stocker 209, and thematerial pallet 203 is drawn out from the material stocker 201 by meansof the pallet transport device 204 of the material stocker 201. A vacuumtransport mechanism M is provided. A sheet workpiece W picked up fromthe pallet 203 is connected on the work pallet 211, which is transportedinto the setting station 205. The pallet 211 supporting a workpiece W istransported from the setting station 205 into the temporary stocker 209by means of the pallet transport device 212. When all pallets 211supporting the workpiece W are stored in the temporary stocker 209, oneof the pallets 211 supporting the workpiece W is drawn out from thetemporary stocker 209 into the setting station 205, and then rightwardlytransported into the work station 214 by means of the belt conveyer 213.When this structure is employed, the entire structure is simplified, andthe cost of designing and manufacturing is reduced. Further, maintenanceis significantly simplified. The automation ability of this system isnot inferior to that of the other examples.

In the example shown in FIG. 35, the station 205 is located at a bottomspace defined within the material stocker 201, where the work pallet 211placed with the workpiece W is moved from the setting station 205 to thefront of the intermediate transport station 301. The pallet P istransported to the intermediate transport station 300 by means of thebelt conveyer 213 and stored in the temporary stocker 209 by means ofthe pallet transport device 212. The work station 214 is located at theother side of the intermediate station 300 near by the temporary stocker209. The work pallet 211 is drawn out from the temporary stocker 209onto the intermediate station 300 by means of the pallet transportdevice 212, and then is transported to work station 214 via a transportpassage R formed at the bottom of the temporary stocker 209 by means ofa belt conveyer 302.

In the example shown in FIG. 36, the setting station 205 is located atthe front of the temporary stocker 209. When the material pallet P isdrawn out from the material stocker 201 by means of the pallet transportdevice 204, a sheet workpiece W is mounted to the work pallet 211 at thesetting station 205 by means of the adhesion work transport mechanism M.After machining of the workpiece W is completed, the pallet 211 isstored in the temporary stocker 214 by means of the pallet transportdevice 212. The work station 214 is located at the opposite side of theintermediate transport station 300 with respect to the temporary stocker209. The work pallet 211 is drawn out from the temporary stocker 209 tothe setting station 205 by means of the pallet transport device 212, andthen to the work station 214 via the transport passage R formed at thebottom of the temporary stocker 209 by the belt conveyer 302.

In the structure shown in FIGS. 35 and 36, since each station andstocker are located in a front and rear manner, installation space ismore efficiently used as compared to other examples having a structurewhich the station and stocker are simply located in a row.

The number of stations in the other examples can be varied according torequirements.

In these examples, the process order and to the sequence can bearranged.

In this embodiment, the number and the structure of the material stocker201, setting station 205, temporary stocker 209 and work station 214 canbe altered as desired.

I claim:
 1. Laser beam machining apparatus having a stocker for storinga plurality of pallets in a shelved manner, each of said palletssecurely carrying a single workpiece thereon, wherein the pallets aretransferred to and machined by a laser processing machine one by one,said laser beam machining apparatus comprising:pallet handling means forselectively drawing a pallet out of the stocker and replacing a palletinto the stocker; an intermediate transport station disposed between thestocker and a laser processing machine, said intermediate transportstation selectively receiving pallets drawn out of the stocker by thepallet handling means and supplying said pallets to the laser processingmachine; transfer means for automatically transferring pallets from theintermediate transport station to the laser processing machine beforethe workpiece is machined and from the laser processing machine to theintermediate transfer station after the workpiece is machined, whereinthe workpiece is kept free from direct contact with the transfer means.2. The laser beam machining apparatus as set forth in claim 1, whereinsaid pallet handling means receives a pallet that supports a machinedworkpiece from the intermediate transfer station to replace the palletin a predetermined position in the stocker.
 3. The laser beam machiningapparatus according to claim 1, further including a setting station inthe vicinity of said intermediate transfer station for placing orremoving a workpiece carried by a pallet.
 4. The laser beam machiningapparatus according to claim 1, further including a workpiece stockerfor pre-storing workpieces to be supplied to an empty pallet at thesetting station.
 5. The laser beam machining apparatus according toclaim 4, further including attaching means for attaching the Workpieceto an empty pallet.
 6. Laser beam machining apparatus comprising:palletstorage means for storing a plurality of pallets and associatedworkpieces in multiple positions within said pallet storage means; alaser beam machine for laser beam machining workpieces carried bypallets from the pallet storage means; first pallet transport means forautomatically transporting a pallet between said pallet storage meansand the laser beam machine; an intermediate transport station fortransporting a pallet drawn from the pallet storage means via said firstpallet transport means to the laser beam machine; said pallet storagemeans for storing at least somes pallets supporting machined workpiecesreturned from the laser beam machine by means of the first pallettransport means to predetermined positions within the pallet storagemeans; and a setting station disposed in the vicinity of saidintermediate transport station for placing or removing workpiecescarried by pallets transported from at least one of the pallet storagemeans and the laser beam machine.
 7. A laser beam machining apparatusaccording to claim 6, further comprising workpiece storing means forstoring workpieces to be supplied to an empty pallet.
 8. A laser beammachining apparatus according to claim 7, further including attachingmeans for attaching the workpiece drawn out from said workpiece storingmeans to an empty pallet.
 9. A laser beam machining apparatus accordingto claim 8, wherein said workpiece storing means stores a plurality ofmaterial pallets supporting one or more workpieces in multiple levelsand further comprising:workpiece transfer means for transferring aworkpiece from one of the multiple levels to an empty pallet; and asecond pallet transport means for transporting a pallet from theworkpiece storing means to the attaching means.
 10. A laser beammachining device according to claim 6, wherein said first pallettransport means includes a) vertically movable lift driven by lift bodydriving means and b) horizontally movable drawing body which is drivenby drawing means, respectively, and a pallet is vertically transportedin accordance with the motion of said lift, and the pallet ishorizontally drawn out from the pallet storage means in accordance withthe motion of the drawing unit.
 11. A method of laser beam machiningworkpieces with a laser processing machine, said workpieces beingindividually supported by pallets which are respectively held by shelvesin a pallet stocker, said method comprising the steps of:drawing one ofsaid pallets and a single workpiece securely carried on said one palletout of the stocker by pallet handling means and carrying the one palletto an intermediate station; transferring the pallet from theintermediate station to a laser processing station by a pallet transferconveyer; machining the workpiece carried on the pallet with the lasermachining machine at the laser processing station; transferring thepallet from the laser processing station to the intermediate station onthe pallet transfer conveyer; and replacing the pallet in apredetermined position in the stocker by the pallet handling means;where each of said steps is performed while maintaining the workpiecefree from direct contact with the pallet transfer conveyer and thepallet handling means.
 12. A method of laser beam machining according toclaim 11, further including a setting station in the vicinity of saidintermediate station and further comprising the step of placing orremoving a workpiece carried by the pallet transported from at least oneof the pallet stocker and the laser processing station.
 13. A method oflaser beam machining according to claim 11, further including aworkpiece stocker for pre-storing multiple workpieces and furthercomprising the step of extracting the workpieces from the workpiecestocker and loading the workpieces onto empty pallets prior to storing acombined workpiece and pallet in the pallet stocker.
 14. A method oflaser beam machining according to claim 13, further including attachingmeans for attaching the workpiece drawn out from said workpiece stockerto the empty pallet and further comprising the step of automaticallyWithdrawing each workpiece and placing said workpiece onto an emptypallet.
 15. A method of laser beam machining according to claim 11,wherein the pallet stocker comprises multiple levels and the palletstocker includes a vertically movable lift driven by lift body drivingmeans and a horizontally movable drawing body which is driven by drawingmeans and wherein a pallet within the pallet stocker is verticallytransported in accordance with the motion of said lift, and ishorizontally drawn out from the pallet stocker by the drawing means.